A new cerium-oxide catalyst developed by researchers at the Department of Energy’s Argonne National Laboratory is showing promise for the efficient reduction of NOx emissions in diesel engine exhaust.

The technology has been under development for a number of years and has a patent pending. A number of companies have expressed interest in licensing the technology and working with Argonne researchers to scale it up and bring it to market. Argonne researcher Christopher Marshall, one of the technology’s developers, believes there could be a commercially available product within two to three years.

The most promising catalyst is Cu-ZSM-5—a zeolite with copper ions attached within its micropore structure—with an external coating of cerium oxide.

Those working previously with Cu-ZSM-5 and similar catalysts in the past found that they performed poorly at removing NOx from diesel exhaust, according to Marshall. Those catalysts require temperatures higher than normal diesel exhaust temperatures and don’t work well in the presence of water vapor, which is almost always found in engine exhausts.

With the help of the Advanced Photon Source at Argonne to analyze the structure and performance of various catalysts, Marshall’s group at Argonne developed an additive that allows Cu-ZSM-5 and similar catalysts to overcome these difficulties.

Our new cerium-oxide additive is the breakthrough that makes it work. When it’s combined with Cu-ZSM-5, the resulting catalyst works at normal exhaust temperatures and is actually more effective with water vapor than without it. With a lean fuel-air mixture, it removes as much as 95-100 percent of NOx emissions.

—Christopher Marshall

The new Argonne catalyst uses the on-board diesel fuel as the reductant; there is no requirement for a separate urea tank for ammonia-selective catalytic reduction. Unlike NOx traps that are platinum-based, the Argonne catalyst contains no platinum and is affected far less by any fuel-borne sulfur.

Marshall says the Argonne catalyst has been tested and performed well with a number of diesel and diesel-type fuels, including standard diesel, synthetic diesel, biodiesel and JP-8. Having performed well in these tests, the next step is to subject the catalyst to engine testing, which will soon take place soon at Argonne's Diesel Engine Test Facility.

Marshall expects these tests will show that in addition to its other advantages, the Argonne catalyst has a greater life expectancy than other catalysts currently on the market.

Marshall and his colleagues are also working with the Chemical Engineering Division’s fuel cell research group. Using a reformer developed by this group could provide better fuel for the catalyst, said Marshall.

Our catalyst already works well, but it would work even better with the smaller hydrocarbons produced by a reformer.

—Christopher Marshall

Initial research on the cerium-oxide catalyst was funded by the US Department of Energy’s Office of Energy Efficiency and Renewable Energy. The catalyst was developed for chemical plant emissions under a joint research agreement with BP. Research plans call for expanded work aimed at both diesel and natural gas engines and coal-fired power plants.

Emissions controls don't increase the efficiency of ICEs; emissions controls are passive devices and in almost all cases reduce engine efficiency. The American driver is under attack by the auto companies to buy diesel power but I for one believe it is too late to the party. Diesel will neither move us off foreign oil nor reduce CO2; it's a step backwards not forward. If someone wants to do something outstanding, get us off fossil fuel asap. BEVs anyone?

When battery costs come down so that the vehicle is sub-$20k, when I can recharge a BEV in ten minutes on a long roadtrip, when I can drive 300 miles on a charge, I'll switch. Until then PHEVs, HEVs, and yes, diesel (running biodiesel) will likely have a bigger role.

As for the automakers being "late to the party" for diesels, I blame overly-stringent anti-smog emissions regs. However, it's advances like this that might actually make them achievable for a reasonable cost.

There are other reasons why it is beneficial to remove as much sulphur from the fuel. Sulphur has a large impact on soot formation; the lower the sulphur content, the less soot is created during combustion. (Bio-diesel is virtually sulphur-free, in Europe 3-8 ppm sulphur diesel is economically viable to produce (Net price at the pump around here is, however, 0,493 EUR/liter (2,54 USD/gal); including taxes, this amounts to 5,57 USD/gal EU-average for diesel right now.

As long as gasoline is dead-cheap in the US (even less expensive than water), sulphur removal is not going to be economically viable unless required by legislation.

However, diesel engines can be operated "lean" - with higher soot output, or "hot" with higher NOx output (but less soot).

since regulations regarding diesel engines are very relaxed in europe, soot removal was easier to do (demanded from public) than removal of NOx; NOx content in the exhaust is still allowed 5 times the levels of gasoline engines around here.

Otoh, "hotter" operations in a diesel cycle would also increase it's efficiency somewhen, so if the soot formation is low enough for this kind of catalyst to operate efficiently over the required miles (150-250 000), I would think it won't come as a net efficiency decrease (lower milage), but also the milage wouldn't increase by much over the inheritent ~15% higher volumetric energy content of diesel fuel.

Just a remainder: Diesel is denser, contains more energy per liter (gallon) than gasoline; at the same engine efficiencies, a diesel must demonstrate approx 15% higher (volumetric) milage over a gasoline engine. One would expect an even higher milage gain as the diesel cycle is supposed to be more efficient, but thats more often than not no longer the case with all the exhaust cleaning and auxilliary equipment necessary for a diesel engine (turbo, high-pressure pump, particulate/nox catalyst, ...)

This technology sounds very. sililiar to diesel additives produced in Britain. Originally it was thought that the peroxide substance would reduce fuel consumption by 10% but recent press accounts indicate the figure is closer to 5%-but every little bit helps.

(a) every modern LDV diesel engine is equipped with a two-way oxidation catalyst based on platinum whose job is to bring HC and CO emissions under the legal limit. Engine-out emissions of these compounds are already much lower than from gasoline engines but still too high. Therefore, low sulphur fuel is still very desirable for high life expectancy of this device. The US has already cut over from 300ppm to 15ppm, EU countries have until 2010 to cut over from 50ppm to 10ppm (some already have).

(b) the catalyst described above accelerates the well-known reburning mechanism for NOx reduction. It#s good to have yet another alternative, but it's not clear how much the catalyst will cost or how much extra fuel its operation will consume.

(c) @Lad: diesels do produce 20-40% less CO2 per kWh than spark ignition engines do. Also, there are many more ways to produce diesel fuel substitutes (biodiesel and xTL from a variety of feedstocks).

BEVs would be great but right now, demand in the LDV market is not in the same place as battery technology. This applies to initial cost, performance and longevity. Start-ups like Tesla Motors or Phoenix may succeed in defining new LDV market segments but it's very early days yet. We won't in a position to abandon ICE R&D for many years yet.

Cleaner ICE diesel, hybrids and PHEVs for light, medium and heavy trucks, tractors, intercity buses etc would be worthwhile to reduce GHG and pollution from those vehicles. At least, until such time as affordable pure electric or highly electric dominant vehicles (all sizes) come to the market.

Peugeot has been working on a clean diesel PHEV car for some time now. Any news?

Is a standardized, scalable, light weight, affordable, clean, flex-fuel, (diesel?), mass produced, highly effcient, on-board generator, possible? It would be a challenge for universities/vehicle builders to design and for countries with low labour cost to produce for worldwide distribution.

Meanwhile, pure electric delivery trucks are coming to the market place in England, France and Italy. Is that the final solution?

diesel hybrids are technologically possible but far too expensive for mass production to make sense. Last I read, the premium was well in excess of EUR 6000 compared to the base vehicle with a similarly powerful NA gasoline engine. For reference, most of Peugeot's cars retail in the EUR 10,000-30,000 price range.

Delivery trucks are a totally different market and, not just because businesses can write off the steep depreciation on their tax returns. The duty cycles are also very different from your average LDV. Logistically, fleet operators can more easily justify installing outdoor recharging stations on company property. As for "final solution", that's a very poor choice of words.

There are developments inDME in China:
We see great potential for DME as a clean alternative fuel . The present diesel oil is a major source of air pollution from diesel engine of trucks and busses in large city like Tokyo. The potential market of diesel oil substitute is larger than LPG. DME is one of ideal fuel for diesel engine. DME vehicles were demonstratively manufactured in Japan, China and Korea and their driving test already started. Practical durability fleet test of a DME truck is under going in Japan.

We are pleased to organise a conference on China taking the lead in the DME market in production from coal and Japan and Korea activities.

If you would like to know more on COAL to Syngas to DME developments, join us at upcoming North Asia DME / Methanol conference in Beijing, 27-28 June 2007, St Regis Hotel. The conference covers key areas which include:

DME productivity can be much higher especially if
country energy policies makes an effort comparable to
that invested in increasing supply.
By:
National Development Reform Commission NDRC
Ministry of Energy for Mongolia

Production of DME/ Methanol through biomass
gasification could potentially be commercialized
By:
Shandong University completed Pilot plant in Jinan and
will be sharing their experience.

Advances in conversion technologies are readily
available and offer exciting potential of DME as a
chemical feedstock
By: Kogas, Lurgi and Haldor Topsoe

Available project finance supports the investments
that DME/ Methanol can play a large energy supply role
By: International Finance Corporation